Improvement in safety center-pinions for watches



J. A. SMITH. Safety Center-Pinion fnr Watches.

No. 217,419. Patented July 8,1879.

I placed therein, and equal in length to the ra- UNITED STATES PATENTOFFICE.

JACOB A. SilllTH, OF SALEM, OHIO, ASSIG'NOR OF ONE-HALF HIS RIGHT TOCHARLES F. KESSELMIRE.

IMPROVEMENT lN SAFETY CENTER-PINIONS FOR WATCHES.

Specification forming part of Letters Patent No. 2] 7,419, dated July 8,1879; application filed May 6, 1879.

To all about it may concern:

Be it known that I, JAooB A. SMITH, of Salem, in the county ofOolumbiana and State of Ohio, have invented certain new and usefulImprovements in Safety Oenter-Pinions for atches, of which the followingis a specification.

In watch-movements, in the event of the breaking of the mainsprin g, thereverse movement of the barrel or winding gear is liable to break theteeth of the wheels of the train; and to avoid such contingency manyplans have been devised for connecting the pinion which engages with thebarrel-gear, and called the center-pinion, with its arbor in a manner toallow this pinion to be disengaged from its arbor, and, turning fieelythereon with the re verse movement of the barrel, save the train frominjury.

My improvement is a new device for this purpose, and it is adapted foruse with the cen terpinion and its arbor as commonly made. This is animportant matter in such devices, while at the same time my improvementhas extreme simplicity, and there is nothing in it that can get out oforder.

1 provide that part of the arbor on which the center-pinion is placedwith a pocket or drilled hole, which extends about two-thirds throughits diameter, with one side radial, and the other, extending from thebottom of the hole, widens outward, forming a flaring hole at one sideof a radial line, and with its oblong end crosswise the arbor and itsinner closed end extending past the axis of the arbor, so as to form thebearing or pivot point for a pin dial side of the hole. The pinion isfitted with a smooth bore upon the arbor over the hole and the outer endof the pin seated therein, so that the forward pull of the pinion will,by the frictional contact of the end of the pin against the smooth wallof the pinion-bore, cause the pin to move or shift upon its inner pointas a pivot awa Y from the radial side of the hole and to describe an areoutside of that of the arbor circumference, and thereby cause the pin tobind against the wall of the pinion-bore and lock or connect the pinionand its arbor in a manner that such connection will not only beeffective, but will be instantly released or disengaged in case of thereverse movement of the barrelgear from any cause. This action of ashii'table pivot-pin within an arbor hole or pocket, and at right anglesto the axis of the arbor, forms a sort of dead-center to the pinion,beyond which said pinion cannot pass in turning in one direction, butwhich deadcenter is destroyed the instant said pinion is turned in theother direction to free said pinion from its arbor.

Referring to the accompanying drawings, Figure 1 represents an axialsection of a center-pinion and its arbor of a watch-movement embracingmy invention; Fig. 2, a cross-section of the same, showing theindependently-shiftable arbor-pin in a position out of radius to lockthe pinion and arbor; Fig. 3, a similar section, showing the arbor-pinin a radial position to free the pinion from its arbor-lock and allowitto turn backward in the contingency stated; Fig. at, the arbor and itspin seated in the hole therein, and Fig. 5 the same with the pin removedfrom the drilled hole.

The watchniovement may be of the usual construction of movements, inwhich a going barrel drives the train, and, as these things are wellunderstood to those skilled in the art, I deem it unnecessary to showother than the parts known as the reversible center-pin and its arbor,being the parts only to which my improven'ients apply, and which arerepre sented upon an enlarged scale.

The arbor a and the center or third pinion, I), are like those now usedin watches, and the bore of the pinion is titted to turn freely upon thearbor. In that part of the arbor on which the center-pinien is seated Idrill a hole, 0, about twothirds the diameter of the arbor, with oneside, (I, radial and the other, 0, stand ing at one side of the axis,and widening from the inner end,f, said flaring side giving an oblongform to said hole, into which hole a pin, 9, is seated, having alengthequal to that of the radial side of said hole. The inner end of the hole0 forms a pivot-bearing, f, for the pin, and the flaring form of saidhole adapts the pin for independent shiftin g movement upon saidbearing-point within the arbor, at right angles to its axis. Thebearing-point of the pin being at one side of and beyond the axis of thearbor, the outer end of the pin,

therefore, in being moved or shifted upon its pivot-point away from theradial side of the hole, will describe an are outside of and differentfrom that forming the circumference of thearbor. This movement of thepin is caused by the frictional contact of the end of the pin againstthe wall of the pinion-bore as the pinionis pulled forward; and as thepin cannot yield in the direction of its length, it must, in movingthrough its eccentric are, lock or engage the pinion with the arbor aseflectually as if the parts were keyed together, because the pin forms asort of dead-center,beyond which the pinion cannot move on the arbor;

but, should the mainspring break, the pull upon the center-pinion willbe reversed, and the pin, by its end frictional contact therewith, willbe moved in parallel position with the radial line of the flaring hole,and thus bring the end of the pin coincident with the circumference ofthe arbor and free the pinion from its hold therewith, allowing it toturn freely with thereverse movement of the barrel, and save the trainfromdamag'e.

The movementot' the pin for the purpose stated is very slight, and thepinion can be fitted closely upon the arbor.

I claim- 1. In safety center-pinions for watches, the

of the breaking of the mainspring, substantially as described.

2. A safety center-pinion for watches, consisting of the pinion 11,adapted to turn freely upon its arbor a, the arbor provided with thepocket 0, extending in depth beyond the axis of said arbor, with oneside radial and the other flaring outward crosswise from an innerpivot-forming socket, and a pin, g, having a'fixedtpivot-seat, f, insaid pocket, and adapted for movement only at'its outer end within theoblong cross flaring pocket, sub- 'stan'tiall y as and for the purposeset forth.

In testimony whereof I have hereunto set my hand in the presence of twowitnesses.

JAcoB AfSMITH.

Witnesses AMos RANK, S. F. REED.

